1. Field of the Invention
The present invention relates to an encapsulating sheet and an optical semiconductor element device, to be specific, to an optical semiconductor element device used for an optical application and an encapsulating sheet used therein.
2. Description of Related Art
Conventionally, as a light emitting device that is capable of emitting high-energy light, a white light emitting device has been known.
In the white light emitting device, for example, blue light is emitted by an optical semiconductor and a part of the emitted blue light is converted into yellow light by a phosphor layer containing a phosphor, so that white light is emitted by color mixing of the blue light and the yellow light.
In recent years, in the white light emitting device, in order to improve extraction efficiency of the light from the optical semiconductor and reduce angle dependence of color tone, a configuration of separating the phosphor layer from the optical semiconductor has been considered.
As the white light emitting device, for example, a semiconductor light emitting device including an LED, a phosphor cover housing the LED in the internal space thereof, and a resin encapsulating material filling in the space between the LED and the phosphor cover has been proposed (ref: for example, Japanese Unexamined Patent Publication No. 2001-358368).